%0 Journal Article %A Susumu Kodama %A Yuichi Yamazaki %A Masahiko Negishi %T Pregnane X Receptor Represses HNF4α Gene to Induce IGFBP1 that Alters Morphology of and Migrates HepG2 Cells %D 2015 %R 10.1124/mol.115.099341 %J Molecular Pharmacology %P mol.115.099341 %X Upon treatment with the pregnane X receptor (PXR) activator rifampicin (RIF), human hepatocellular carcinoma HepG2-derived ShP51 cells that stably express PXR showed epithelial-mesenchymal transition (EMT)-like morphological changes and migration. Our recent DNA microarrays identified hepatocyte nuclear factor (HNF) 4α and insulin-like growth factor-binding protein (IGFBP) 1 mRNAs to be down- and up-regulated, respectively, in RIF-treated ShP51 cells, and these regulations were confirmed by the subsequent real-time PCR and western blot analyses. Using this cell system, we demonstrated here that the PXR-HNF4α-IGFBP1 pathway is an essential signal for PXR-induced morphological changes and migration. First, we characterized the molecular mechanism underlying the PXR-mediated repression of the HNF4α gene. Chromatin conformation capture and chromatin immunoprecipitation (ChIP) assays revealed that PXR activation by RIF disrupted enhancer-promoter communication and prompted de-acetylation of histone H3 in the HNF4α P1 promoter. Cell-based reporter and ChIP assays showed that PXR targeted the distal enhancer of the HNF4α P1 promoter and stimulated dissociation of HNF3β from the distal enhancer. Subsequently, siRNA knockdown of HNF4α connected PXR-mediated gene regulation with the PXR-induced cellular responses, showing that the knockdown resulted in the up-regulation of IGFBP1 and EMT-like morphological changes without RIF treatment. Moreover, recombinant IGFBP1 augmented migration, whereas an anti-IGFBP1 antibody attenuated both PXR-induced morphological changes and migration in ShP51 cells. PXR indirectly activated the IGFBP1 gene by repressing the HNF4α gene, thus enabling up-regulation of IGFBP1 to change the morphology of ShP51 cells and cause migration. These results provide new insights into PXR-mediated cellular responses toward xenobiotics including therapeutics. %U https://molpharm.aspetjournals.org/content/molpharm/early/2015/07/31/mol.115.099341.full.pdf